So-called resin laminates are conventionally employed for interior materials of automobiles, building materials, and materials for logistics and packaging. Such resin laminate has a front surface material made of a resin and a back surface material made of a resin. The back surface material is provided with concave ribs having tip ends to be abutted on the internal surface of the front surface material. For a method of manufacturing such resin laminate, various methods have been employed conventionally.
For example, PTL 1 discloses a method as follows.
That is, using a split mold in which a cavity in one piece of the split mold is provided with a plurality of projections projecting towards the other piece of the split mold, two sheet materials made of a thermoplastic resin in a molten state is positioned between the pair of split mold pieces. Then, after an enclosed space is formed between one of the sheet materials and the cavity in the one piece of the split mold, the air in the enclosed space is sucked from the side of the one piece of the split mold. By the suction action, a plurality of concave ribs are formed in the sheet material at the plurality of projections. By closing the pair of split mold pieces, the bottom of the concave ribs is welded to the other sheet material to obtain a resin laminate having a hollow structure reinforced by the plurality of ribs.
Use of such manufacturing technique enables maximum thinning of the respective thicknesses of the two sheet materials, thereby enabling reduction in weight and thickness while securing the manufacturing efficiency and the product quality.